Python – 替代列表元素作为键值对

给定一个列表，通过将替代元素映射为键值对将其转换为字典。

Input : test_list = [2, 3, 5, 6, 7, 8]
Output : {3: 6, 6: 8, 2: 5, 5: 7}
Explanation : Alternate elements mapped to get key-value pairs. 3 -> 6 [ alternate]

Input : test_list = [2, 3, 5, 6]
Output : {3: 6, 2: 5}
Explanation : Alternate elements mapped to get key-value pairs. 3 -> 6 [ alternate]

方法#1：使用循环

这是可以执行此任务的方法之一。在此，我们迭代两次以获取两个替代元素以获得所需的所有替代键值字典。

Python3

# Python3 code to demonstrate working of 
# Alternate Elements Dictionary
# Using loop
  
# initializing list
test_list = [2, 3, 5, 6, 7, 8, 9, 10] 
  
# printing original list
print("The original list is : " + str(test_list))
  
res = dict()
  
# pairing first set of Alternate elements 
for idx in range(len(test_list) - 2):
    if idx % 2:
        res[test_list[idx]] = test_list[idx + 2]
  
# pairing other set
for idx in range(len(test_list) - 2):
    if not idx % 2:
        res[test_list[idx]] = test_list[idx + 2]
  
# printing result 
print("The extracted dictionary : " + str(res))

输出

The original list is : [2, 3, 5, 6, 7, 8, 9, 10]
The extracted dictionary : {3: 6, 6: 8, 8: 10, 2: 5, 5: 7, 7: 9}

方法#2：使用字典理解+列表切片

这是可以执行此任务的另一种方式。在这里，我们切出两个替代元素列表并使用字典理解进行配对。

蟒蛇3

# Python3 code to demonstrate working of 
# Alternate Elements Dictionary
# Using dictionary comprehension + list slicing 
  
# initializing list
test_list = [2, 3, 5, 6, 7, 8, 9, 10] 
  
# printing original list
print("The original list is : " + str(test_list))
  
# extracting lists
list1 = test_list[1::2]
list2 = test_list[::2]
  
# constructing pairs using dictionary comprehension
res = {list1[idx] : list1[idx + 1] for idx in range(len(list1) - 1)}
res.update({list2[idx] : list2[idx + 1] for idx in range(len(list2) - 1)})
  
# printing result 
print("The extracted dictionary : " + str(res))

输出

The original list is : [2, 3, 5, 6, 7, 8, 9, 10]
The extracted dictionary : {3: 6, 6: 8, 8: 10, 2: 5, 5: 7, 7: 9}